Gradual degeneration of liquid superlubricity: Transition from superlubricity to ordinary lubrication, and lubrication failure

Xiao, Chen; Li, Jinjin; Gong, Jian; Chen, Lei; Zhang, Jiyang; Qian, Linmao; Luo, Jianbin

doi:10.1016/j.triboint.2018.10.008

Cited by 12 publications

(3 citation statements)

References 36 publications

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“…After that, to optimize the adhesion strength between the film and substrate, a ~55 nm thick nitrogen doped H-DLC film as a buffer layer was first grown on the silicon wafers in working atmosphere of a mixture of methane and nitrogen. Finally, the H-DLC film was deposited as lubricating layer in the mixed gases of methane and hydrogen [19]. The film thickness was measured as around 870 nm based on observation of the cross section using a scanning electron microscope.…”

Section: Experimental Materials and Methodsmentioning

confidence: 99%

Key Role of Transfer Layer in Load Dependence of Friction on Hydrogenated Diamond-Like Carbon Films in Humid Air and Vacuum

et al. 2019

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The friction of hydrogenated diamond-like carbon (H-DLC) films was evaluated under the controlled environments of humid air and vacuum by varying the applied load. In humid air, there is a threshold applied load below which no obvious friction drop occurs and above which the friction decreases to a relatively low level following the running-in process. By contrast, superlubricity can be realized at low applied loads but easily fails at high applied loads under vacuum conditions. Further analysis indicates that the graphitization of the sliding H-DLC surface has a negligible contribution to the sharp drop of friction during the running-in process under both humid air and vacuum conditions. The low friction in humid air and the superlow friction in vacuum are mainly attributed to the formation and stability of the transfer layer on the counterface, which depend on the load and surrounding environment. These results can help us understand the low-friction mechanism of H-DLC film and define optimized working conditions in practical applications, in which the transfer layer can be maintained for a long time under low applied load conditions in vacuum, whereas a high load can benefit the formation of the transfer layer in humid air.

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Section: Experimental Materials and Methodsmentioning

confidence: 99%

Key Role of Transfer Layer in Load Dependence of Friction on Hydrogenated Diamond-Like Carbon Films in Humid Air and Vacuum

et al. 2019

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“…Phosphoric acid superlubricity is also applicable to other friction pairs, such as Si 3 N 4 /SiO 2 , ceramic/sapphire, and sapphire/ruby [87,89,90]. However, the accumulated pressure and heat from friction will inevitably damage the liquid based tribofilm [91][92][93]. Therefore, it is urgent to strengthen the protective film to resist high contact pressure in fabricating superlubricity surface.…”

Section: Superlubricitymentioning

confidence: 99%

Low friction of superslippery and superlubricity: A review

et al. 2022

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The issues regarding energy dissipation and component damage caused by the interface friction between a friction pair attract enormous attention to friction reduction. The key-enabling technique to realize friction reduction is the use of lubricants. The lubricants smooth the contact interfaces, achieving an ultralow friction contact, which is called superslippery or superlubricity. At present, superslippery and superlubricity are two isolated research topics. There is a lack of unified definition on superslippery and superlubricity from the viewpoint of tribology. Herein, this review aims at exploring the differences and relations between superslippery and superlubricity from their origin and application scenarios. Meanwhile, the challenges for developing superslippery surface and superlubricity surface are discussed. In addition, perspectives on the interactive development of these two surfaces are presented. We hope that our discussion can provide guidance for designing superslippery or superlubricity surfaces by using varies drag-reduction technologies.

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“…Various studies worldwide have successfully measured the surface and interface force by using SFA, thereby greatly contributing to the introduction of aqueous lubrication and its mechanism. − Meanwhile, the hydrodynamic effect makes an important contribution to aqueous lubrication, especially in the stable ultralow friction coefficient (μ) stage. In most macrotypical tribological processes, a running-in process is necessary for the achievement of ultralow friction, ,− which helps smooth the contacting surfaces and reduce the collision among asperities. The running-in process of most aqueous lubrications is divided into three periods: a high-friction region (the first region), a friction-decreasing region (the second region), and a stable, ultralow μ region. ,− , …”

Section: Introductionmentioning

confidence: 99%

On Lubrication States after a Running-In Process in Aqueous Lubrication

et al. 2019

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Recently, many studies have reported the ultralow friction coefficient of sliding friction between rigid solid surfaces in aqueous lubrication. A running-in process that goes through high-friction and friction-decreasing regions to a stable ultralow friction region is often required. However, the role of the friction-decreasing region is often ascribed to tribofilm formation in which complexity hindered the quantitative description of the running-in process and the prediction of its subsequent lubrication state. In this work, the frictional energy (E f) dissipated in the running-in process of a poly(oligo(ethylene glycol) methyl ether acrylate) aqueous lubrication was related to the wear of solid surfaces under different conditions and lubrication states. Experimental results indicated that the high-friction region was in a boundary lubrication state, contributed to most of the wear, and significantly reduced the contact pressure, whereas the friction-decreasing region was in a mixed lubrication state, contributed only to the slight and slow removal of materials, and slightly reduced the contact pressure. Therefore, by establishing relationships among the wear scar diameter, E f, and the Stribeck curve of the tribological system, the subsequent lubrication state after a running-in process under various working loads and sliding speeds could be quantitatively predicted. The running-in experiments with different aqueous lubrication systems showed good agreement with the prediction of this method. This investigation provides an effective method for the wear and lubrication state prediction after a running-in process, further proving the importance of the Stribeck curve for a lubrication system. This study may also have important implications for the strategy design of the running-in process in various industrial applications.

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Gradual degeneration of liquid superlubricity: Transition from superlubricity to ordinary lubrication, and lubrication failure

Cited by 12 publications

References 36 publications

Key Role of Transfer Layer in Load Dependence of Friction on Hydrogenated Diamond-Like Carbon Films in Humid Air and Vacuum

Key Role of Transfer Layer in Load Dependence of Friction on Hydrogenated Diamond-Like Carbon Films in Humid Air and Vacuum

Low friction of superslippery and superlubricity: A review

On Lubrication States after a Running-In Process in Aqueous Lubrication

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